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Sen. Marco Rubio has managed to win just three contests in the 2016 primary season

His home state of Florida votes Tuesday

Miami (CNN)Marco Rubio likely didn't expect the final days before the Florida primary to go quite like this.

Nearly a year ago, the Florida senator launched his campaign here with a soaring speech at the Freedom Tower, a building that was used to process Cuban refugees fleeing the Castro regime decades ago.

But in the days ahead of a contest that could end his campaign, Rubio has instead been making urgent appeals to his constituents to support him once again as he tries to take out Republican front-runner Donald Trump.

"We have to win here in Florida," Rubio said at a recent event in Hialeah, seemingly begging the crowd. "Hialeah believed in me (in 2010). I'm asking you to believe in me now."

"I am focused on one thing right now," he told reporters a few days later at a synagogue in West Palm Beach, and that is winning the state of Florida, and then moving on in my campaign."

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He's even working to appeal to voters who may not support him -- but are against Trump.

"I'm telling people in Florida the truth: A vote for Ted Cruz or a vote for John Kasich in Florida is a vote for Donald Trump," Rubio said in West Palm Beach. "Any vote that doesn't go to me in essence is helping Donald Trump to win. ... If Donald Trump wins by one vote, he will take 99 delegates."

It's a far cry from the start of the campaign for the native son, who throughout the campaign has leaned heavily on his autobiography of growing up the child of two Cuban immigrants mostly in Southern Florida. But that narrative has struggled to resonate after Trump took the GOP race by storm.

So far, Rubio has managed to win just three contests in the 2016 primary season.

Rubio's struggles

Going into Super Tuesday 3, Rubio is trailing Trump in Florida by double digits, 40% to 26%, according to CNN's poll of polls. He's down in the delegate race by more than 200 to Trump, a gap that can't be closed by Florida's winner-take-all contest alone.

Still, some of his supporters say they aren't discouraged.

"There is no worry," said Yeybarth Lopez, a young IT professional who drove down from Tennessee to volunteer in Florida for Rubio. "All eyes on Florida right now. We can't wait for him to win."

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A Venezuelan, she compared Trump to the late dictator Hugo Chavez, and said that's a message that resonates with immigrants from authoritarian countries.

"Venezuelans fear that Trump is going to be like the next Chavez, the way that Chavez the Venezuelan president, the way he won people is by lying and saying those politicos are incorrect and you don't need another politician anymore, choose me. And that is what Trump is doing," she said.

But other supporters were very aware their candidate is struggling in the polls.

"We're hoping and praying that people wake up and just think hard about our future as a country, and the way the polls are looking, it's very concerning," said Stephanie Christiansen, a stay-at-home mom from Davie, Florida. "Anything is possible. If I didn't think there was any hope, I wouldn't be here."

"Anything is possible," echoed Daniel Tyson, a Naval science instructor and veteran from Broward County. "It's going to be close."

His girlfriend, Miami personal trainer Jennie Bakker said she was ""very worried right now."

"I think Trump getting the win is definitely going to be devastating," she said. "Just worried, hoping for the best, praying for the best."

Rubio was even greeted by a doubter at a retail stop in Naples, Florida, who held up a sign encouraging him to throw his support behind rival Texas Sen. Ted Cruz.

"Sen. Rubio, THE TEA PARTY & I ELECTED you and SEN. Cruz. Please endorse Ted before March 15. Your time will come soon," read the homemade sign from John Moore.

Pulling out the stops

Volunteers have poured into the state from across the country. Like Lopez, a man from Seattle was at the Hialeah rally, piggy-backing a volunteer trip on business travel. Another volunteer from New York was helping to staff the Miami office on Thursday afternoon as phone bankers in English and Spanish diligently made their calls.

"Darling, fire under your a--," one woman said emphatically in a call to a friend. "We have to win Florida," she said. Call "everyone" and get them to volunteer, she added.

Campaign spokesman Alex Burgos estimated hundreds if not thousands of volunteers are being deployed in the state, not to mention millions in on-air buys by the Rubio campaign and a supportive super PAC.

Rubio is hitting all parts of the state, from the Panhandle to the southern counties. But the campaign is banking heavily on running up the score in South Florida, where Rubio leads in the polls, to help offset Trump's strength in central and northern parts of the state.

The campaign has also been making a concerted effort to encourage voters to either cast their ballots early or absentee. Rubio led Trump 48% to 23% among the nearly 20% of voters who had already voted, according to a Monmouth poll.

"I think he's going to get a very strong turnout in Miami-Dade County," Florida Rep. Carlos Curbelo told reporters after the CNN Republican debate in Miami on Thursday night. "I think Hispanic Republicans are already turning out in very high numbers and that is going to continue. ... And Marco Rubio has a great shot. Is it going to be close? Absolutely, but he's still in it."

His supporters are quick to say that the county has more Republicans than any other in the state, as well.

"I think you're going to see the Miami-Dade turnout be something of historic proportions," Rubio's Florida Co-Chairman Adam Hasner said in West Palm Beach.

Photos:Moments from Marco Rubio's career

Photos:Moments from Marco Rubio's career

Florida Sen. Marco Rubio speaks in October 2013 at the Values Voter Summit, held by the Family Research Council in Washington.

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Photos:Moments from Marco Rubio's career

Sen. Mike Lee, left, and Rubio talk before a news conference to introduce their proposal for an overhaul of the tax code in March.

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Photos:Moments from Marco Rubio's career

Rubio, center, arrives in the House chamber ahead of Israeli Prime Minister Benjamin Netanyahu's address to a joint meeting of the U.S. Congress in March.

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Photos:Moments from Marco Rubio's career

Rubio speaks with the media after delivering remarks during the graduation of small business owners from the Goldman Sachs 10,000 Small Businesses program held in Miami in February.

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Photos:Moments from Marco Rubio's career

Rubio talks to aides in December before speaking on President Barack Obama's announcement about revising policies on U.S.-Cuba relations.

Rubio talks to reporters in June after a closed door briefing on Capitol Hill.

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Photos:Moments from Marco Rubio's career

Rubio speaks to the media in front of a wall dedicated to the victims of the violence in Venezuela as he shows support for the Venezuelan community at a restaurant in Doral, Florida, in April 2014.

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Photos:Moments from Marco Rubio's career

Rubio speaks to the media at the Doral restaurant in April 2014.

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Photos:Moments from Marco Rubio's career

Rubio checks his phone in March as he arrives for a Capitol Hill news conference to introduce a proposal for an overhaul of the tax code.

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Photos:Moments from Marco Rubio's career

Rubio, left, is greeted as he arrives at a restaurant in Doral in February 2014.

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Rubio, left, and Florida Gov. Rick Scott speak to the media in Doral in February 2014.

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From left, Sens. Cory Booker, Rubio, Kristen Gillibrand and John McCain wait for Obama to deliver the State of the Union address in January 2014.

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Rubio addresses an event held by the American Enterprise Institute for Public Policy Research in January 2014.

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Paralympian Brad Snyder poses with Rubio during a Team USA Congressional visit in November 2013.

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Photos:Moments from Marco Rubio's career

Rubio speaks in November 2013 during a campaign stop for Virginia Attorney General Ken Cuccinelli, the Republican candidate for governor of Virginia.

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Rubio confers with McCain as U.S. Ambassador to Syria Robert Ford testifies before the Senate Foreign Relations Committee in October 2013.

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Rubio, center, speaks to members of the media as Sen. Ron Johnson, left, and Rep. Ron DeSantis listen during a news conference on Capitol Hill in October 2013.

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Rubio returns to the Capitol after meeting with Obama and other Republican leaders about the government shutdown in October 2013.

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Rubio speaks to an aide on Capitol Hill as he arrives for the weekly Senate Republican Policy Committee luncheon in September 2013.

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Miami-Dade GOP Chairman Nelson Diaz, who supports Rubio in a private capacity, gave Rubio a slight edge to win.

"I think Marco's got a 60% chance of winning Florida," Diaz said. "I think it's clearly between him and Trump, and the question is how much damage did Ted Cruz do (with advertising) in the last week before the end."

"It's not over until it's over," former Florida Rep. Lincoln Diaz-Balart said, channeling Yogi Berra, as he warmed up and tried to encourage the crowd in Hialeah.

Rubio, for his part, is fond of saying he's an "underdog," noting that he chased an incumbent governor out of the Republican primary to win his Senate seat six years ago.

He's discounting the polls showing him down in most cases by double digits -- citing a state he ultimately lost by three points as evidence.

"Polls were wrong in Virginia," Rubio said in West Palm Beach, noting that the surveys showed him trailing by a wide margin before his close second place. "I would have beat (Trump) if I had another two days of campaigning," he added.